New scatter formula

main.cpp

@@ -21,7 +21,7 @@ color ray_color(const ray& r, const hittable& world, int32_t depth)
     hit_record rec;
     if (world.hit(r, 0.001, INFINITY, rec))
     {
-        point3 target = rec.p + rec.normal + random_in_unit_sphere();
+        point3 target = rec.p + rec.normal + random_in_hemisphere(rec.normal);
         return 0.5 * ray_color(ray(rec.p, target - rec.p), world, depth-1);
     }
     vec3 unit_direction = normalize(r.direction);

vec3.hpp

@@ -159,4 +159,20 @@ vec3 random_in_unit_sphere()
     }
 }
 
+// Returns a normalized version of the above vector
+vec3 random_unit_vector()
+{
+    return normalize(random_in_unit_sphere());
+}
+
+vec3 random_in_hemisphere(const vec3& normal)
+{
+    vec3 in_unit_sphere = random_in_unit_sphere();
+    
+    if (dot(in_unit_sphere, normal) > 0.0)
+        return in_unit_sphere;
+    else
+        return -in_unit_sphere;
+}
+
 #endif